| Summary: | Thesis (M.Sc.)--Memorial University of Newfoundland, 1997. Biology Bibliography: leaves 69-76. Snow crabs exhibiting macroscopic evidence of Hematodinium sp. infection were collected off the east coast of Newfoundland during the period 1993 to 1996. Infected crabs were collected over a large area but prevalence of infection was low. Pathology of the internal organs in affected crabs was observed in association with the developmental stages of Hematodinium sp. The parasite invaded hemal spaces causing disruption of normal tissue morphology, and ultimately mortality of the host. Hematodinium sp. developed through three distinct morphological stages during the progress of infection: vegetative, multinucleate prespore and dinospore. The latter is the final stage within the crab. These stages of the parasite developed synchronously and sequentially within any one crab, but might differ between individual crabs. The ultrastructure of these stages was examined using electron microscopy, which revealed the following characteristics in all developmental stages: the presence of many trichocysts, mitochondria with tubular cristae and vacuoles with lipid-like material. In the dinospore stage, flageila and micropores were observed in addition to the other common features. The morphological characteristics of Hematodinium sp. described in this investigation conform to previous descriptions of Hematodinium spp. reported from a variety of crabs inhabiting different geographic regions.
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